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Biomedical subjects

G Geyer

Publications and source records attributed to G Geyer.

At least 73 records · Page 4Linked to original sources
PubMed1982

Remarks on the spatial structure of the external segment of glycophorin A.

A model of the possible structure of the N-terminal part of glycophorin A is suggested. According to this model, in isotonic salt solutions of physiologic pH the peptide chain of the extracellular segment of glycophorin A is arranged parallel to the membrane with its carbohydrate side chains orientated perpendicularly to the lipid bilayer. Decreases of the pH or of the ionic strength result in a structural remodeling of this segment, there is at the very least a partial detachment of the glycosylated peptide backbone from the membrane's lipid layer.

Chemical Phenomena↗
PubMed1982

[Ganglioneuroma of the cervical sympathetic nerve in combination with Salmonella infection].

A 70-year-old patient who was seen for evaluation of a parapharyngeal abscess is reported. Since clinical recovery could not be achieved by incision and Salmonella typhi-murium was isolated from the wound-swabs, the existence of two different affections at the same time was apparent. The histological examination after surgical excision led to the diagnosis of a ganglioneuroma. When the patient returned after one year with the clinical aspect of recurrence of the tumour, this pattern could not be verified; Salmonella typhi-murium, however, was found again in the former wound and the stool, too. The etiology of focal manifestations in connection with gastroenteric salmonella-borne infections is discussed.

Aged↗
PubMed1982

[Incidence of otitis externa following swimming pool attendance--a case study in 6 indoor pools].

A bacteriological study of the microflora in the auditory meatus of patients with otitis externa after swimming in correlation to the water flora was done during winter 80/81. Six indoor-pools (monthly controls ahead had proven unobjectionable water quality) were analyzed daily, while all swimmers were asked to come for otologic examination whenever symptoms of otitis externa appeared. In a control group without otitis externa the auditory canal was inspected and swabs were taken immediately after swimming. The results indicate, that a short term contamination of the ear canal is possible by swimming in water of unobjectionable quality; this however does not necessarily lead to clinical appearances. Since the incidence of otitis externa in our study (0.01%) was not higher than the morbidity rate in nonswimmers, the data support the concept of the multiplex etiology for otitis externa.

Bacteria↗
PubMed1981

A polyacrylamide gel method for the cytochemical demonstration of glucose-6-phosphate dehydrogenase activity in mouse sperm.

Solubility and low activity of glucose-6-phosphate dehydrogenase let both the aqueous and agarose gel cytochemical incubation techniques fail in mouse sperm. By means of a polyacrylamide gel medium G6PDH was constantly demonstrated in the midpieces of sperm cells prefixed with cold acetone. Although this technique prevented the dislocation of the enzyme, diffusion artifacts due to delayed formation of formazan may occur from sites of high dehydrogenase activity, e.g., epididymal epithelium encountered in sperm smears.

Acrylic Resins↗
PubMed1981

The endocrinology of testicular germinal cell tumors.

Oestradiol (Oe2), testosterone (T), lutenizing hormone (LH), follicle stimulating hormone (FSH), beta-human chorionic gonadotrophin (beta-hCG) and alpha-1 foetoprotein (AFP) were measured in blood samples taken from 63 patients with testicular tumours. In patients without tumour recurrence (n=31) AFP, Oe2 and T were within the normal range, beta-hCG was negative, LH levels were marginally elevated and FSH concentrations were significantly elevated. In patients with tumor recurrence (n=32) Oe2 was significantly elevated, whereas the T levels varied considerably and were therefore statistically not different from the patients without tumour recurrence. The beta-hCG positive subgroup of the recurrence group, however, demonstrated significantly elevated T levels. T levels were highest in patients with 51 to 500 U beta-hCG/1. On hand T was normal or even low normal in beta-hCG negative -AFP positive patients. In all subgroups decreasing FSH levels and decreasing LH responses to LRH were among the earliest signs of tumour recurrence. The observations suggest that moderate hCG levels are able to stimulate testicular T production, whereas high levels no longer increase T serum concentrations. Increased conversion rates form steroid precursors to oestradiol seem to be a feature of beta-hCG positive as well as beta-hCG negative testicular tumours.

Choriocarcinoma↗
PubMed1981

[Influence of aging on glucose tolerance and insulin secretion (author's transl)].

Oral and intravenous glucose tolerance tests were performed in three different age groups, separately for men and women. Blood glucose and insulin levels were examined. Advanced age is associated with reduced glucose tolerance independent whether it is investigated by means of intravenous or oral glucose application. Concomitant examination of plasma insulin, however, differentiates between the intravenous and the oral glucose tolerance test. While the high insulin levels after oral glucose administration are rather increasing with age, the minor insulin reaction after the intravenous glucose route is decreasing with advancing age. Results of the intravenous and the oral glucose tolerance test reveal no difference between male and female subject as long as blood sugar is examined. However, insulin levels and the insulinogenic index are consistently higher in men than in women.

Adult↗
PubMed1981

Lipid segregation from human erythrocyte tethers.

Fluid shear force may deform point-attached erythrocytes to become droplike shaped and anchored by a single long or 2-4 short tethers. By addition of glutaraldehyde to the medium the cells were fixed such as to stabilize this deformation for ensuing SEM, freeze-fracture, fine structural, and ultrahistochemical studies. Freeze-fracture specimens revealed identical numbers and distribution patterns of membrane particles in both the membrane of tethers and of the droplike portions of red cells. Segregated vesicles most often were located adjacent to the attachment site of the tether. All of the vesicles were devoid of membrane particles. Irrespective of their length, the tethers were about 0.1 micrometer in diameter. Cross-sections of the tether membrane and the plasmalemma of the major part of the cell appeared identical. Ultrahistochemical studies revealed the same intensity of iron binding capacity and affinity to ferritin labelled anti AHP at either area of the deformed erythrocyte membrane. Segregating vesicles were also stained by colloidal iron and by fer-anti AHP. By means of the DAB-reaction no haemoglobin was demonstrated within the vesicles. All of these findings corroborate the notion, that lipid molecules were segregated from the membrane whose curvature increased considerably during the formation of the tether.

ABO Blood-Group System↗
PubMed1981

Erythrocyte vesiculation. 2. Membrane molecular transformation.

A population of vesicles 150 +/- 30 nm in diameter was isolated from banked human blood and the perturbation of their membrane studied. SDS polyacrylamide gel electrophoresis revealed the complete loss of spectrins from the vesicle membrane which was also depleted of various intrinsic proteins. In particular, severe reduction of protein 3 and glycophorin is consistent with the over 80% decline of intramembrane particles in either fracture face of the vesicle membrane. The stimulation of vesicle acetylcholinesterase is considered indicative of an initial disintegration associated with the segregation and rearrangement of membrane constituents. The findings are discussed with regard to the subcellular mechanisms of erythrocyte vesiculation.

Blood Preservation↗
PubMed1981

[The creatine levels--a criterion for preservation damage in erythrocytes?].

The creatine content of human erythrocytes decreases during in vivo ageing. On the other hand, banking of erythrocytes in ACD-AG- or CPD-medium, respectively, causes an initial distinct increase with following slow decrease of the creatine level. When compared with the initial value the creatine content is still elevated after 6 weeks of banking. Hitherto, the reason of this behaviour is unknown. The creatine content does not represent a suitable criterion for banking related damage of erythrocytes.

Blood Preservation↗
PubMed1981

[Importance of the cell membrane for the sequestration of aged erythrocytes].

The erythrocyte membrane is an important cell organelle which determines the intravital life time of the cell in a decisive way. Their mechanic properties are closely connected with the metabolism of the cells. Increasing disturbance of the cellular metabolism especially in the course of biological aging leads to enhanced cell rigidity. It is supposed that the decreased elasticity of the aged erythrocytes in critical regions of the blood circulation (capillaries with a diameter of 2.5 to 3.0 micrometers) leads to pressure induced vesiculation and spherocytosis. It is possible that also IgG-receptors are demarked by this process. After passing a threshold concentration as immunobiological signals increased irreversible binding of IgG induces the sequestration of the erythrocytes by the erythrocyte destructing system.

Animals↗
PubMed1981

Deformability of erythrocytes incubated at various pH-values.

The deformability of human erythrocytes was studied at pH values ranging from 6.4 to 8.5 using micropipette aspiration of whole cells. Also the mean cell volume was measured in dependence on pH. The observed high increase of the transit pressure pt with lowering of the pH in a fairly narrow interval suggests that within the range of pH values under consideration pi is mainly controlled by the effect of the critical volume of the cells.

Erythrocytes↗
PubMed1981

Defined rearrangement of the membrane of banked erythrocytes.

Segregation of integrated proteins, detachment of actin and spectrin from cytoplasmic aspect as well as decomposition of phospholipids may cause the release of vesicles from spicula of banked erythrocytes. The findings provide evidence for a mechanism of plasmalemmal rearrangement, because a clear distinction between the protein composition of the vesicle membrane and of the erythrocyte plasmalemma could be shown. The vesiculation mechanism is discussed.

Actins↗
PubMed1981

[Maturation processes in the plasmalemma of erythroid cells].

Quantitative studies of the enucleating normoblast show that the plasmalemma envelope of the nucleus under extrusion and this of the nucleus that appear to be extruded bind more autologous IgG than the plasmalemma of the future reticulocyte. This finding explains the quick phagocytosis of the extruded nuclei by macrophages. In addition heaps of small vesicles free from haemoglobin are found at the enucleating normoblasts and at the reticulocytes. They bind cationized ferritin and autologous IgG. They are interpreted as segregation of constituents of the plasmalemma during red blood cell maturation.

Binding Sites, Antibody↗
PubMed1981

[Production and extracellular arrangement of proteoglycans in the growing hyaline cartilage].

Fixation of hyaline cartilage with potassium ferricyanide in addition to glutaraldehyde and osmium tetroxide leads to a better stabilization of the glycosaminoglycans. The resulting chelate formation enhances the electronmicroscopic density. In active chondrocytes electron dense material is found intracellularly in the rough endoplasmic reticulum, in transport vesicles, in the Golgi apparatus and in big vacuoles. Intercellularly large amounts of the glycosaminoglycans are preserved. The correlations between the macromolecules and the collagenous fibrills are demonstrated.

Animals↗